PURPOSE: To reduce interference sound and peeling sound and to decrease noise of an entire outdoor unit by arranging a filament machine of a guard net radially in a logarithmic spiral.

CONSTITUTION: A front surface grill 10 is mounted at a wake flow side of a diffuser of a blower for externally diffusing the air from an impeller through the diffuser. A guard net of the grill 10 is arranged at a filament machine 11 in a logarithmic spiral. Thus, a resistance of a flow of the air to be discharged from the impeller can be reduced, peeling from a front surface grill guard is decreased to reduce noise. An enlarging angle of the logarithmic spiral is set to 30-40 degrees to most effectively reduce a resistance of the net to the flow of the air to be discharged from the impeller.